Import custom file format into Blender
One easy solution, though kind of "hacky", would be to append "v " (a lowercase v and a space) to the beginning of each line, and then importing it has a Wavefront .obj format.

So just do: print "v " + '%.2f %.2f %.2f %.2f'%(vec[0],vec[1],vec[2],vec[3])

In this example three vertices are defined, then they are automatically assigned an index from top to bottom;

v 0.00 1.00 0.00 0.00 #This is the index 1
v 0.10 0.99 0.10 0.10 #This is the index 2
v 0.20 0.98 0.20 0.20 #This is the index 3


Then, to define a "face" (a connection of 2 or more vertices) use:

f 1 2 3


Using this will define a face between the vertices of index 1, 2 and 3.

If, however, you want to only connect vertices with edges, you can use:

l 1 2


To define an edge between vertices  of index 1 and 2.

If you want a brief explanation, there's a Wikipedia page. For the complete specification, refer to this page.